Context-Based Audio Decoder with Dynamic Reset Mechanism

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Solution Overview

Problem

Traditional audio coding methods experience a significant bitrate overhead due to the need for regular transmission of detailed codebook selection information, which can lead to inefficient encoding and decoding, especially when audio content deviates from expected spectral distributions.

Innovation Solution

An audio decoder and encoder that employ a context-based entropy decoding system with a side-information-based reset mechanism, allowing the context to be reset between audio frames or within frames, even when spectral resolution remains unchanged, to adapt to changing audio content and reduce bitrate inefficiencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If context-based entropy decoding is used to exploit correlations in audio signals, then bitrate efficiency is improved, but the system becomes less reliable when audio content deviates from expected spectral distributions

Engineering Contradiction:
Improvebitrate efficiencyVSAvoiddecoding reliability under spectral deviation
Core Design Contradiction:
Loss of energyVSReliability

Solution Approach 1:

The patent implements dynamic context resetting based on spectral analysis. The system transitions from a static context model to a dynamic one where the context is reset when spectral deviations are detected. This allows the system to adapt its behavior (using context or resetting) based on the actual audio content characteristics, resolving the contradiction between exploiting correlations and handling deviations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses feedback from spectral analysis to control context resetting. By analyzing the spectral content and detecting deviations from expected distributions, the system receives feedback that triggers appropriate context management actions. This feedback mechanism ensures reliability under spectral deviation while maintaining bitrate efficiency during normal conditions.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If detailed codebook selection information is transmitted regularly, then decoding accuracy is improved, but bitrate overhead increases significantly

Engineering Contradiction:
Improvedecoding accuracyVSAvoidbitrate overhead
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the necessary codebook selection information based on actual spectral deviations rather than transmitting detailed codebook selection information regularly. By taking out only the essential information needed for accurate decoding under deviation conditions, the system reduces bitrate overhead while maintaining decoding accuracy when needed.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter of codebook selection information transmission from a fixed high-detail mode to a variable mode that adapts to spectral conditions. This parameter change allows the system to transmit minimal information during normal conditions (reducing bitrate overhead) while ensuring accurate decoding information is available when spectral deviations occur.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If context is reset frequently to adapt to changing audio content, then adaptability is improved, but more bits are required for encoding the reset decisions

Engineering Contradiction:
Improvecontext adaptation to audio contentVSAvoidbit demand for context reset signaling
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies local quality by resetting the context only in specific local situations where spectral deviations are detected, rather than resetting frequently or uniformly. This localized context resetting approach maintains adaptability where needed while minimizing the bit demand for reset signaling in stable regions.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses partial action by implementing context resetting only partially - specifically when spectral deviation criteria are met - rather than applying it excessively or continuously. This partial resetting strategy achieves necessary adaptability while keeping the bit demand for encoding reset decisions to a minimum.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP3671736A1Audio decoder, audio encoder, method for decoding an audio signal, method for encoding an audio signal, computer program and audio signal
Publication Date: 2020.06.24 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3671736A1 patent drawingFigure 1
  • EP3671736A1 patent drawingFigure 2
  • EP3671736A1 patent drawingFigure 3A~3B

AI summary

An audio decoder for providing a decoded audio information on the basis of an entropy encoded audio information comprises a context-based entropy decoder configured to decode the entropy-encoded audio information in dependence on a context, which context is based on a previously-decoded audio information in a non-reset state-of-operation. The context-based entropy decoder is configured to select a mapping information, for deriving the decoded audio information from the encoded audio information, in dependence on the context. The context-based entropy decoder comprises a context resetter configured to reset the context for selecting the mapping information to a default context, which default context is independent from the previously-decoded audio information, in response to a side information of the encoded audio information.